Distal renal tubular acidosis, hypokalemic paralysis, nephrocalcinosis, primary hypothyroidism, growth retardation, osteomalacia and osteoporosis leading to pathological fracture: a case report

Unusual presentation of Sjogren's syndrome

Sjogren's syndrome is a known cause of renal tubular acidosis (RTA). However, osteomalacia associated with Sjogren's syndrome is rare and seldom reported in literature. We report a case of pseudofractures of both femora due to osteomalacia as a result of RTA secondary to Sjogren's syndrome, which was initially misdiagnosed as a stress fracture. A man in his 30s presented with hip pain and was initially misdiagnosed to have stress fractures because of the 'through and through' extension of the 'fracture' lines at the neck of both femora. The patient had a normal serum biochemistry profile except for elevated alkaline phosphatase levels. On further evaluation, he was found to have distal RTA secondary to Sjogren's syndrome. The patient responded to sodium bicarbonate therapy with clinical, biochemical and radiological improvement. A high index of suspicion for RTA should be kept in a patient with osteomalacia with a normal calcium profile and vitamin D level.

Recurrent hypokalemic paralysis in hypothyroidism

Hypothyroidism, a commonly encountered thyroid disorder, usually manifests with readily recognizable typical features. However, an unusual presentation of a classic thyroid disorder may hinder accurate diagnosis in certain instances. One such rare initial presentation of hypothyroidism is recurrent hypokalemic paralysis, and existing reports in the literature are sparse. It has been more commonly reported in thyrotoxicosis. We report the case details and clinical outcomes of two middle-aged individuals (a 34-year-old male and a 37-year-old female) with recurrent episodes of hypokalemic paralysis. Their clinical examination revealed pure motor hyporeflexia quadriparesis with hypotonia and diminished deep tendon reflexes without any autonomic dysfunction. They had no significant previous medical history. Biochemical findings revealed hypokalemia in both cases (1.4 and 1.9 mEq/L, respectively) with elevated levels of thyroid‑stimulating hormone and thyroid‑related antibodies in both individuals, thus, confirming the diagnosis of autoimmune hypothyroidism. Immediate treatment with intravenous and oral potassium correction helped in the recovery. Thyroxine supplementation was considered a follow-up treatment, and for a one-year follow-up period there were no complaints of limb weakness reported in both individual.

Osteoporosis Complicating Renal Tubular Acidosis in Association With Sjogren's Syndrome

Chronic metabolic acidosis increases alkali mobilization from the bone and promotes the development of osteoporosis. We report the case of a 35-year-old Caucasian female who presented for surgical fixation of a left femoral fracture sustained six months previously from a ground level fall with known primary hypothyroidism (for 12 years, on thyroxine replacement) with history of hypokalemia for the last 13 years (on regular oral potassium supplements). There was no history of fracture in past. There was no history of renal stones. There was positive history of hypokalemic periodic paralysis twice in past (12 and 13 years back). There was no history of recurrent oral or ocular ulcers. On examination there was no uveitis, oral ulcers, lacrimal or parotid gland enlargement. Upon workup the patient was diagnosed with left-sided femur fracture (neck) and was admitted for surgical management. She underwent left dynamic hip screw fixation under general anesthesia which she tolerated well. Upon further workup she had normal anion gap with hyperchloremic metabolic acidosis, low vitamin D level and dual-energy x-ray absorptiometry (DEXA) scan revealed osteoporosis at femur and hip joint. Vitamin D was replaced, she was started on Ibandronate and calcium supplements. Her further workup revealed positive anti-SSA. Our final clinical diagnosis in this case is possible or incomplete Sjogren's syndrome causing type-1 renal tu-bular acidosis (RTA; distal RTA) with osteoporosis.

Primary Hyperaldosteronism and Renal Medullary Nephrocalcinosis: A Controversial Association

Primary hyperaldosteronism (PA) is a common disease with a prevalence of 5–10% in unselected patients with hypertension. Medullary nephrocalcinosis is a radiological diagnosis and refers to diffuse calcification in the renal parenchyma. The three commonest causes of nephrocalcinosis are hyperparathyroidism, distal renal tubular acidosis, and medullary sponge kidney. PA is not a recognized cause of nephrocalcinosis. There are a few case reports linking PA with nephrocalcinosis published till date. In this case series, we report three cases where PA was possibly associated with medullary nephrocalcinosis. In all three cases, the common causes of nephrocalcinosis were excluded by careful clinical history, biochemical evaluation, and radiological findings. We conclude and emphasize that a diagnosis of PA as an etiology of medullary nephrocalcinosis should be sought after common causes have been excluded, at least in those with hypertension that is difficult to control.

Association of urinary acidification function with the progression of diabetic kidney disease in patients with type 2 diabetes

OBJECTIVE

Although diabetic kidney disease (DKD) has been considered as a glomerulocentric disease in the past few decades, growing evidence demonstrated that tubular damage was indispensable in its pathogenesis and progression. This study was designed to investigate the association of urinary acidification dysfunction with the progression of DKD in type 2 diabetic patients.

METHODS

Here the urinary acidification functions were measured from 80 participants with renal biopsy-proven DKD. The different kinds of renal tubular transportation dysfunction were analyzed, including the dysfunction of bicarbonate reabsorption, titratable acid secretion, and ammonium secretion. In addition, patients were followed up for 17 (interquartile range, 11-32) months to evaluate the effect of urinary acidification dysfunction in the progression of DKD.

RESULTS

The most common urinary acidification dysfunction was the disorder of ammonium secretion, accounting for 53.75%. The more proteinuria excretion and the lower glomerular filtration rate (GFR) were observed in the urinary titratable acid disorder group than the normal group, and the same results were obtained for ammonium secretion disorder. Urine titratable acid was positively correlated with eGFR whereas it was inversely correlated with proteinuria, serum creatinine, and BUN. Moreover, 24 h urine protein, serum creatinine, BUN and cystatin C increased from DKD stage II to stage IV, whereas the eGFR and urine titratable acid decreased in the same way. Furthermore, Kaplan-Meier analysis and Cox regression showed that the disorder of titratable acid was an independent risk factor for DKD progression.

CONCLUSIONS

The dysfunction of urinary titratable acid is a potential biomarker for the severity of proteinuria, eGFR and glomerular lesions in patients with DKD. Moreover, the titratable acid disorder is an independent risk factor of the DKD progression.

A novel homozygous deletion in ATP6V0A4 causes distal renal tubular acidosis: A case report

RATIONALE

Autosomal recessive distal renal tubular acidosis (dRTA) is a rare condition, most cases of which are caused by genetic mutations. Several loss-of-function mutations in the ATP6V0A4 gene have been recently reported.

PATIENT CONCERNS

A 2-month, 24-day-old Chinese girl presenting with vomiting and diarrhea.

DIAGNOSIS

dRTA was established by metabolic acidosis and hypokalemia. Mutational analysis of the ATP6V0A4 gene revealed a homozygous deletion of exons 13 and 14. The father was found to have a heterozygous loss of both exons, whereas the mother was normal.

INTERVENTIONS

Patient was treated with potassium citrate.

OUTCOMES

The patient has shown normal pH and potassium levels.

LESSONS

This is the first case of a homozygous deletion in ATP6V0A4 reported in the literature. Although the initial auditory screening was normal in this case, this patient will nevertheless undergo long-term auditory testing.

Primary biliary cirrhosis with refractory hypokalemia: A case report

RATIONALE

Renal tubular acidosis (RTA) represents a class of metabolic disorders characterized by metabolic acidosis with a normal plasma anion gap. As a rare complication of primary biliary cirrhosis (PBC), RTA is easily overlooked, likely leading to misdiagnosis.

PATIENT CONCERNS

A 32-year-old woman who had been diagnosed with PBC at our hospital was found to have hypokalemia due to repeated fatigue for 2 years, and the etiology was unknown.

DIAGNOSES

Due to the laboratory test results, radiographic findings, and pathologic results, she was diagnosed with PBC associated with RTA.

INTERVENTIONS

She was then treated with ursodeoxycholic acid, potassium citrate, and calcium supplements together with activated vitamin D.

OUTCOMES

Thus far, the patient showed a good response to ursodeoxycholic acid, and the clinical symptoms and liver function were significantly improved.

LESSONS

Physicians that encounter refractory hypokalemia in a patient with PBC should be aware of the presence of RTA. The early diagnosis and treatment of such patients are of paramount importance to alleviate clinical symptoms and delay disease progression.

Case Report: Recurrent hypokalemic periodic paralysis associated with distal renal tubular acidosis (type 1) and hypothyroidism secondary to Hashimoto's thyroiditis

Background: Hypokalemic periodic paralysis (HypoKPP) is characterized by transient episodes of flaccid muscle weakness. We describe the case of a teenaged boy with HypoKPP and hyperthyroidism due to Hashimoto's thyroiditis with initial manifestation of renal tubular acidosis. This combination is rare and little described previously in men. Case presentation: A 17-year-old boy was admitted after three days of muscular weakness and paresthesia in the lower limbs with an ascending evolution, leading to prostration. Decreased strength was found in the lower limbs without a defined sensory level, reduced patellar and ankle reflexes. Positive antithyroid antibodies were found. He received hydration treatment, IV potassium and levothyroxine, with which there was a clinical improvement. Other examinations led to the diagnosis of type 1 renal tubular acidosis. Conclusion: HypoKPP is a rare disorder characterized by acute episodes of muscle weakness. Type 1 renal tubular acidosis can occur as a consequence of thyroiditis, which is explained by the loss of potassium. This combination is unusually rare, and has not been described before in men. The etiopathogenesis of the disease as well as a dynamic explanation of what happened with the patient are discussed in this report.

Case Report: Recurrent hypokalemic periodic paralysis associated with distal renal tubular acidosis (type 1) and hypothyroidism secondary to Hashimoto's thyroiditis

Background: Hypokalemic periodic paralysis (HypoKPP) is characterized by transient episodes of flaccid muscle weakness. We describe the case of a teenaged boy with HypoKPP and hyperthyroidism due to Hashimoto's thyroiditis with initial manifestation of renal tubular acidosis. This combination is rare and little described previously in men.

Case presentation: A 17-year-old boy was admitted after three days of muscular weakness and paresthesia in the lower limbs with an ascending evolution, leading to prostration. Decreased strength was found in the lower limbs without a defined sensory level, reduced patellar and ankle reflexes. Positive antithyroid antibodies were found. He received hydration treatment, IV potassium and levothyroxine, with which there was a clinical improvement. Other examinations led to the diagnosis of type 1 renal tubular acidosis.

Conclusion: HypoKPP is a rare disorder characterized by acute episodes of muscle weakness. Type 1 renal tubular acidosis can occur as a consequence of thyroiditis, which is explained by the loss of potassium. This combination is unusually rare, and has not been described before in men. The etiopathogenesis of the disease as well as a dynamic explanation of what happened with the patient are discussed in this report.

Successful Management of Refractory Type 1 Renal Tubular Acidosis with Amiloride

A 28-year-old female with history of hypothyroidism, Sjögren's Syndrome, and Systemic Lupus Erythematosus (SLE) presented with complaints of severe generalized weakness, muscle pain, nausea, vomiting, and anorexia. Physical examination was unremarkable. Laboratory test showed hypokalemia at 1.6 mmol/l, nonanion metabolic acidosis with HCO₃ of 11 mmol/l, random urine pH of 7.0, and urine anion gap of 8 mmol/l. CT scan of the abdomen revealed bilateral nephrocalcinosis. A diagnosis of type 1 RTA likely secondary to Sjögren's Syndrome was made. She was started on citric acid potassium citrate with escalating dosages to a maximum dose of 60 mEq daily and potassium chloride over 5 years without significant improvement in serum K⁺ and HCO₃ levels. She had multiple emergency room visits for persistent muscle pain, generalized weakness, and cardiac arrhythmias. Citric acid potassium citrate was then replaced with sodium bicarbonate at 15.5 mEq every 6 hours which was continued for 2 years without significant improvement in her symptoms and electrolytes. Amiloride 5 mg daily was added to her regimen as a potassium sparing treatment with dramatic improvement in her symptoms and electrolyte levels (as shown in the figures). Amiloride was increased to 10 mg daily and potassium supplementation was discontinued without affecting her electrolytes. Her sodium bicarbonate was weaned to 7.7 mEq daily.

Hashimoto Thyroiditis and Nephrocalcinosis in a Child with Down Syndrome

Introduction:

Hypothyroidism has been reported to affect renal function and structure. However, the association of hypothyroidism with distal renal tubular acidosis (dRTA) is rarely reported in children.

Case Presentation:

We present a 6-year-boy with Down syndrome admitted in our department due to vomiting, weakness, polyuria, polydipsia, irritability and weight loss in the last few weeks. Investigations revealed features of hypokalemia, metabolic acidosis and alkaline urine consistent with dTRA. Abdominal ultrasound found nephrocalcinosis. In addition, Antithyroid peroxidase antibodies were positive, suggesting an autoimmune background for the pathogenesis of the tubular dysfunction. Treatment for dRTA and hypothyroidism was started and symptomatic improve was noticed.

Conclusion:

dRTA should be excluded in children with autoimmune disorders who develop weakness, polyuria, polydipsia or growth failure. Early diagnosis would reduce long-term complications.

Bone matrix, cellularity, and structural changes in a rat model with high-turnover osteoporosis induced by combined ovariectomy and a multiple-deficient diet

In estrogen-deficient, postmenopausal women, vitamin D and calcium deficiency increase osteoporotic fracture risk. Therefore, a new rat model of combined ovariectomy and multiple-deficient diet was established to mimic human postmenopausal osteoporotic conditions under nutrient deficiency. Sprague-Dawley rats were untreated (control), laparatomized (sham), or ovariectomized and received a deficient diet (OVX-Diet). Multiple analyses involving structure (micro-computed tomography and biomechanics), cellularity (osteoblasts and osteoclasts), bone matrix (mRNA expression and IHC), and mineralization were investigated for a detailed characterization of osteoporosis. The study involved long-term observation up to 14 months (M14) after laparotomy or after OVX-Diet, with intermediate time points at M3 and M12. OVX-Diet rats showed enhanced osteoblastogenesis and osteoclastogenesis. Bone matrix markers (biglycan, COL1A1, tenascin C, and fibronectin) and low-density lipoprotein-5 (bone mass marker) were down-regulated at M12 in OVX-Diet rats. However, up-regulation of matrix markers and existence of unmineralized osteoid were seen at M3 and M14. Osteoclast markers (matrix metallopeptidase 9 and cathepsin K) were up-regulated at M14. Micro-computed tomography and biomechanics confirmed bone fragility of OVX-Diet rats, and quantitative RT-PCR revealed a higher turnover rate in the humerus than in lumbar vertebrae, suggesting enhanced bone formation and resorption in OVX-Diet rats. Such bone remodeling caused disturbed bone mineralization and severe bone loss, as reported in patients with high-turnover, postmenopausal osteoporosis. Therefore, this rat model may serve as a suitable tool to evaluate osteoporotic drugs and new biomaterials or fracture implants.

Double osteomalacia

A 35-year old woman presented, with chronic vague ill health, subacute symptoms of decreased appetite, increased thirst, excessive urination, and rib pains, and acute quadriparesis. On evaluation, she was found to have type 1 Renal tubular acidosis, pseudofractures of ribs and Hypovitaminosis D. Administration of oral solution containing potassium citrate and citric acid along with pharmacological doses of Vitamin D and supportive treatment improved her condition remarkably. This case report highlights interesting coexistence of two disorders, one very common (Hypovitaminosis D) and one rare (Distal Renal Tubular Acidosis dRTA), in same patient, producing same pathology (osteomalacia).